Methods and systems for slurry coating

ABSTRACT

The present disclosure provides systems and methods that employ slurries to form layers adjacent to substrates. Such layers can include, for example, one or more of iron, chromium, nickel, silicon, vanadium, titanium, boron, tungsten, aluminum, molybdenum, cobalt, manganese, zirconium, and niobium, oxides thereof, nitrides thereof, sulfides thereof, or combinations thereof. In some examples, such layers are stainless steel layers.

CROSS-REFERENCE

This application is a continuation application of U.S. patentapplication Ser. No. 15/673,107, filed Aug. 9, 2017, which is acontinuation application of International Patent Application Serial No.PCT/US2016/017155, filed Feb. 9, 2016, which claims priority to U.S.Provisional Patent Application Ser. No. 62/114,560, filed Feb. 10, 2015,and U.S. Provisional Patent Application Ser. No. 62/232,161, filed Sep.24, 2015, each of which is entirely incorporated herein by reference.

BACKGROUND

Steel can be an alloy of iron and other elements, including carbon. Whencarbon is the primary alloying element, its content in the steel may bebetween 0.002% and 2.1% by weight. Without limitation, the followingelements can be present in steel: carbon, manganese, phosphorus, sulfur,silicon, and traces of oxygen, nitrogen and aluminum. Alloying elementsadded to modify the characteristics of steel can include withoutlimitation: manganese, nickel, chromium, molybdenum, boron, titanium,vanadium and niobium.

Stainless steel can be a material that does not readily corrode, rust(or oxidize) or stain with water. There can be different grades andsurface finishes of stainless steel to suit a given environment.Stainless steel can be used where both the properties of steel andresistance to corrosion are beneficial.

SUMMARY

The present disclosure provides systems and methods for forming materiallayers using slurries. Examples of such material layers include but arenot limited to stainless steel, silicon steel, and noise vibrationharshness damping steel.

The present disclosure provides systems and methods that employ slurriesto form layers adjacent to substrates. Such layers can include, forexample, one or more of iron, chromium, nickel, silicon, vanadium,titanium, boron, tungsten, aluminum, molybdenum, cobalt, manganese,zirconium, and niobium, oxides thereof, nitrides thereof, sulfidesthereof, or combinations thereof.

In an aspect, the present disclosure provides a slurry for forming atleast one layer comprising at least one elemental metal adjacent to asubstrate, comprising: (a) a solvent; (b) an alloying agent, wherein thealloying agent comprises the at least one elemental metal, and whereinthe alloying agent is configured to diffuse to or into the substrate;(c) a halide activator that facilitates diffusion of the at least oneelemental metal to the substrate; and (d) an inert species that aids indispersing the alloying agent in the solvent, wherein the inert specieshas a particle size that is less than or equal to about 200 mesh.

In some embodiments, the alloying agent is configured to diffuse intothe substrate. In some embodiments, a particle size of the alloyingagent is greater than the particle size of the inert species. In someembodiments, the particle size of the alloying agent is less than about140 mesh. In some embodiments, the alloying agent comprises carbon. Insome embodiments, the alloying agent comprises a transition metal. Insome embodiments, the alloying agent is selected from the groupconsisting of iron, chromium, nickel, silicon, vanadium, titanium,boron, tungsten, aluminum, molybdenum, cobalt, manganese, zirconium,niobium and combinations thereof. In some embodiments, the alloyingagent is a ferroalloy of a transition metal. In some embodiments, thealloying agent is selected from the group consisting of ferrosilicon(FeSi), ferrochrome (FeCr), chromium and combinations thereof. In someembodiments, the alloying agent is a salt or an oxide. In someembodiments, at least one elemental metal is a transition metal. In someembodiments, the at least one elemental metal is selected from the groupconsisting of chromium, nickel, aluminum, silicon, vanadium, titanium,boron, tungsten, aluminum, molybdenum, cobalt, manganese, zirconium,niobium and combinations thereof.

In some embodiments, the halide activator includes a monovalent metal, adivalent metal or a trivalent metal. In some embodiments, the halideactivator is selected from the group consisting of magnesium chloride(MgCl₂), iron (II) chloride (FeCl₂), calcium chloride (CaCl₂), zirconium(IV) chloride (ZrCl₄), titanium (IV) chloride (TiCl₄), niobium (V)chloride (NbCl₅), titanium (III) chloride (TiCl₃), silicon tetrachloride(SiCl₄), vanadium (III) chloride (VCl₃), chromium (III) chloride(CrCl₃), trichlorosilane (SiHCl₃), manganese (II) chloride (MnCl₂),chromium (II) chloride (CrCl₂), cobalt (II) chloride (CoCl₂), copper(II) chloride (CuCl₂), nickel (II) chloride (NiCl₂), vanadium (II)chloride (VCl₂), ammonium chloride (NH₄Cl), sodium chloride (NaCl),potassium chloride (KCl), molybdenum sulfide (MoS), manganese sulfide(MnS), iron disulfide (FeS₂), chromium sulfide (CrS), iron sulfide(FeS), copper sulfide (CuS), nickel sulfide (NiS), and combinationsthereof. In some embodiments, the halide activator is hydrated. In someembodiments, the halide activator is selected from the group consistingof iron chloride tetrahydrate (FeCl₂.4H₂O), iron chloride hexahydrate(FeCl₂.6H₂O), and magnesium chloride hexahydrate (MgCl₂.6H₂O). In someembodiments, the halide activator is non-corrosive with respect to thesubstrate. In some embodiments, a molar ratio of a halide of the halideactivator to the at least one elemental metal is at most about 10:1. Insome embodiments, the halide activator decomposes to an oxide uponheating. In some embodiments, the halide activator aids in dispersingthe alloying agent in the solvent.

In some embodiments, the inert species is selected from the groupconsisting of alumina (Al₂O₃), silica (SiO₂), titanium dioxide (TiO₂),magnesium oxide (MgO), calcium oxide (CaO), a clay and combinationsthereof. In some embodiments, the clay is Bentonite clay, Monterey clay,Kaolin clay, a philosilicate clay or a combination thereof. In someembodiments, the inert species forms a hydrogen bond with itself and/orthe metal halide activator in the slurry. In some embodiments, theparticle size of the inert species is less than or equal to about 140mesh. In some embodiments, the solvent is an aqueous solvent. In someembodiments, the solvent is an organic solvent. In some embodiments, theorganic solvent is selected from the group consisting of an alcohol, ahydrocarbon, a ketone, and combinations thereof. In some embodiments,the alcohol is a C1 to C8 alcohol. In some embodiments, the solventcomprises an inorganic binder. In some embodiments, the inorganic binderis sodium silicate. In some embodiments, the solvent comprises anorganic binder. In some embodiments, the organic binder is methylcellulose or polyethylene oxide (PEO). In some embodiments, the alloyingagent is configured to be deposited onto a surface of the substrate viaa chemical vapor deposition (CVD) reaction. In some embodiments, thehalide activator acts as a binder when the slurry is dried. In someembodiments, the solvent has a boiling temperature that is less than orequal to about 200° C. In some embodiments, a viscosity of the slurry isfrom about 1 centipoise (cP) to 1,000,000 cP. In some embodiments, aspecific gravity of the slurry is from about 1 to 10. In someembodiments, a shear thinning index of the slurry is from about 1 to 8.In some embodiments, a pH of the slurry is from about 3 to 12.

In another aspect, the present disclosure provides a slurry for formingat least one layer comprising at least one elemental metal adjacent to asubstrate, comprising: (a) a solvent; (b) an alloying agent, wherein thealloying agent comprises the at least one elemental metal, and whereinthe alloying agent is configured to diffuse to or into the substrate;(c) a halide activator that aids in diffusion of the at least oneelemental metal to the substrate, wherein a molar ratio of a halide ofthe halide activator to the at least one elemental metal is at mostabout 10:1; and (d) an inert species that aids in suspending thealloying agent in the slurry. In some embodiments, the alloying agent isconfigured to diffuse into the substrate.

In another aspect, the present disclosure provides a method forproducing a slurry, comprising: (a) providing an alloying agent, ahalide activator, a solvent, and an inert species to a vessel to providea mixture, wherein a particle size of the inert species is less than orequal to about 200 mesh; and (b) subjecting the mixture having thealloying agent, halide activator, solvent and inert species to mixing,thereby producing the slurry.

In some embodiments, the method further comprises, in (a), adding thealloying agent, the halide activator and the inert species to thesolvent to produce the mixture. In some embodiments, the method furthercomprises, in (b), adding an acid to the mixture. In some embodiments,the acid facilitates control of a viscosity and/or stability of theslurry. In some embodiments, the mixing occurs at a shear rate fromabout 1 s⁻¹ to 10000 s⁻¹.

In some embodiments, the alloying agent comprises carbon. In someembodiments, the alloying agent comprises one or more of iron, chromium,nickel, silicon, vanadium, titanium, boron, tungsten, aluminum,molybdenum, cobalt, manganese, zirconium, niobium and combinationsthereof. In some embodiments, the alloying agent is selected from thegroup consisting of ferrosilicon (FeSi), ferrochrome (FeCr), chromiumand combinations thereof.

In some embodiments, the halide activator includes a monovalent metal, adivalent metal or a trivalent metal. In some embodiments, the halideactivator is selected from the group consisting of magnesium chloride(MgCl₂), iron (II) chloride (FeCl₂), calcium chloride (CaCl₂), zirconium(IV) chloride (ZrCl₄), titanium (IV) chloride (TiCl₄), niobium (V)chloride (NbCl₅), titanium (III) chloride (TiCl₃), silicon tetrachloride(SiCl₄), vanadium (III) chloride (VCl₃), chromium (III) chloride(CrCl₃), trichlorosilance (SiHCl₃), manganese (II) chloride (MnCl₂),chromium (II) chloride (CrCl₂), cobalt (II) chloride (CoCl₂), copper(II) chloride (CuCl₂), nickel (II) chloride (NiCl₂), vanadium (II)chloride (VCl₂), ammonium chloride (NH₄Cl), sodium chloride (NaCl),potassium chloride (KCl), molybdenum sulfide (MoS), manganese sulfide(MnS), iron disulfide (FeS₂), chromium sulfide (CrS), iron sulfide(FeS), copper sulfide (CuS), nickel sulfide (NiS) and combinationsthereof. In some embodiments, the halide activator is hydrated. In someembodiments, the halide activator is selected from the group consistingof iron chloride tetrahydrate (FeCl₂.4H₂O), iron chloride hexahyrdate(FeCl₂.6H₂O) and magnesium chloride hexahydrate (MgCl₂.6H₂O). In someembodiments, a molar ratio of a halide of the halide activator to thealloying agent is at most about 10:1. In some embodiments, the inertspecies is selected from the group consisting of alumina (Al₂O₃), silica(SiO₂), titanium dioxide (TiO₂), magnesium oxide (MgO), calcium oxide(CaO), a clay and combinations thereof. In some embodiments, the clay isBentonite clay, Monterey clay, Kaolin clay, a philosilicate clay or acombination thereof.

In some embodiments, the particle size of the inert species is less thanor equal to about 600 mesh. In some embodiments, the solvent is anaqueous solvent. In some embodiments, the solvent is an organic solvent.In some embodiments, the solvent comprises an inorganic binder. In someembodiments, the inorganic binder is sodium silicate. In someembodiments, the solvent comprises an organic binder. In someembodiments, the organic binder is methyl cellulose or polyethyleneoxide (PEO).

In another aspect, the present disclosure provides a method forproducing a slurry, comprising: (a) providing an alloying agent, a metalhalide activator, a solvent, and an inert species to a vessel to providea mixture, wherein a molar ratio of a halide of the halide activator tothe alloying agent is at most about 10:1; and (b) subjecting the mixturehaving the alloying agent, metal halide activator, solvent and inertspecies to mixing, thereby producing the slurry.

In another aspect, the present disclosure provides a method for coatinga substrate with at least one layer comprising at least one elementalmetal adjacent to the substrate, comprising: (a) coating at least aportion of the substrate with a slurry to generate a slurry-coatedsubstrate, wherein the slurry comprises (i) a solvent, (ii) an alloyingagent, wherein the alloying agent comprises the at least one elementalmetal, and wherein the alloying agent is configured to diffuse to orinto the substrate, (iii) a metal halide activator that facilitatesdiffusion of the at least one elemental metal to the substrate, and (iv)an inert species that aids in suspending the alloying agent in thesolvent, wherein the inert species has a particle size that is less thanor equal to about 200 mesh; and (b) subjecting the slurry-coatedsubstrate to annealing under conditions that are sufficient to diffusethe at least one elemental metal to or into the substrate, to generate alayer adjacent to the substrate comprising the at least one elementalmetal.

In some embodiments, the alloying agent is configured to diffuse intothe substrate. In some embodiments, the method further comprises, priorto (b), incubating the slurry-coated substrate at an incubationtemperature greater than a boiling temperature of the solvent, whereinthe solvent is substantially removed from the slurry by evaporation togenerate a dry film on the slurry-coated substrate. In some embodiments,the method further comprises incubating the slurry-coated substrate atthe incubation temperature under vacuum conditions. In some embodiments,the dry film (1) has a green strength suitable to survive flexing to a20 inch diameter arc 20 times (positive and negative) and pass a tapetest with small amount of powdering, and/or (2) is capable of survivinga high speed roll coating process.

In some embodiments, the method further comprises incubating theslurry-coated substrate at the incubation temperature for about 10seconds to 5 minutes. In some embodiments, the incubation temperature isfrom about 50° C. to about 300° C. In some embodiments, the methodfurther comprises, after the incubating, maintaining the slurry-coatedsubstrate having the dry film under vacuum conditions prior to (b). Insome embodiments, prior to (a), the substrate is provided in a coil andthe coil is unwound prior to the coating. In some embodiments, after(a), the unwound coil is wound into a coil. In some embodiments, priorto (a), the substrate is provided as a wire, pipe, tube, slab, a coiledmesh, a dipped formed part, a sheet, a wire rope, or a rod.

In some embodiments, the annealing conditions comprise an annealingtemperature, an annealing time and an annealing atmosphere. In someembodiments, the annealing temperature is from about 800° C. to 1300° C.In some embodiments, the total annealing time is from about 5 hours to200 hours, optionally including cooling, and optionally wherein a timeat a maximum temperature is between 1 hour and 100 hours. In someembodiments, the annealing atmosphere comprises hydrogen (H₂), nitrogen(N₂), argon (Ar) or a combination thereof. In some embodiments, theannealing atmosphere is a vacuum. In some embodiments, in (a), thecoating is via one or more selected from the group consisting of rollcoating, dipping, painting, spin coating, printing, spraying, slotcoating, curtain coating, slide coating, and extrusion coating. In someembodiments, in (a), the coating is via slot coating. In someembodiments, the method further comprises, in (a), coating the at leasta portion of the substrate with the slurry and an additional slurry inat least two cycles. In some embodiments, the slurry and the additionalslurry are different. In some embodiments, the method further comprises,in (a), coating the at least a portion of the substrate with the slurryin multiple cycles. In some embodiments, the method further comprises,in (a), coating the at least a portion of the substrate with the slurryin multiple cycles, wherein the substrate is coated in a pattern.

In some embodiments, in (b), the substrate comprises a residuecomprising the inert species after the subjecting the slurry-coatedsubstrate to the annealing conditions. In some embodiments, after (b),the method further comprises removing the residue from the substrate. Insome embodiments, in (b), the substrate is substantially free ofKirkendall voids after the subjecting the slurry-coated substrate to theannealing conditions. In some embodiments, the substrate comprises oneor more grain pinning particles.

In some embodiments, the one or more grain pinning particles comprises amaterial selected from the group consisting of an intermetallic, anitride, a carbide, a carbonitride of titanium, aluminum, niobium,vanadium and combinations thereof. In some embodiments, the substratedoes not comprise free carbon. In some embodiments, the substrate is ametal-containing substrate. In some embodiments, the metal-containingsubstrate comprises one or more of iron, copper and aluminum. In someembodiments, the metal-containing substrate is steel. In someembodiments, the substrate is a ceramic substrate. In some embodiments,the layer comprises stainless steel. In some embodiments, the layer isan outer layer and the at least one elemental metal has a concentrationthat varies by no more than about 20 wt. % in the outer layer. In someembodiments, the substrate further comprises a bonding layer adjacent tothe outer layer, wherein the at least one elemental metal has aconcentration that decreases to less than about 1.0 wt. % in the bondinglayer.

In some embodiments, the substrate further comprises a core regionadjacent to the bonding layer that comprises substantially the samecomposition as the substrate. In some embodiments, the alloying agentcomprises carbon. In some embodiments, the alloying agent is selectedfrom the group consisting of iron, chromium, nickel, silicon, vanadium,titanium, boron, tungsten, aluminum, molybdenum, cobalt, manganese,zirconium, niobium and combinations thereof. In some embodiments, the atleast one elemental metal is selected from the group consisting ofchromium, nickel, aluminum, silicon, vanadium, titanium, boron,tungsten, aluminum, molybdenum, cobalt, manganese, zirconium, niobiumand combinations thereof. In some embodiments, the alloying agent isselected from the group consisting of ferrosilicon (FeSi), ferrochrome(FeCr), chromium and combinations thereof. In some embodiments, themetal halide activator includes a monovalent metal, a divalent metal ora trivalent metal. In some embodiments, the metal halide activator isselected from the group magnesium chloride (MgCl₂), iron (II) chloride(FeCl₂), calcium chloride (CaCl₂), zirconium (IV) chloride (ZrCl₄),titanium (IV) chloride (TiCl₄), niobium (V) chloride (NbCl₅), titanium(III) chloride (TiCl₃), silicon tetrachloride (SiCl₄), vanadium (III)chloride (VCl₃), chromium (III) chloride (CrCl₃), trichlorosilance(SiHCl₃), manganese (II) chloride (MnCl₂), chromium (II) chloride(CrCl₂), cobalt (II) chloride (CoCl₂), copper (II) chloride (CuCl₂),nickel (II) chloride (NiCl₂), vanadium (II) chloride (VCl₂), ammoniumchloride (NH₄Cl), sodium chloride (NaCl), potassium chloride (KCl),molybdenum sulfide (MoS), manganese sulfide (MnS), iron disulfide(FeS₂), chromium sulfide (CrS), iron sulfide (FeS), copper sulfide(CuS), nickel sulfide (NiS) and combinations thereof.

In some embodiments, the metal halide activator is hydrated. In someembodiments, the metal halide activator is selected from the groupconsisting of iron chloride tetrahydrate (FeCl₂.4H₂O), iron chloridehexahyrdate (FeCl₂.6H₂O) and magnesium chloride hexahydrate(MgCl₂.6H₂O). In some embodiments, a molar ratio of a halide of themetal halide activator to the at least one elemental metal is at mostabout 10:1. In some embodiments, the inert species is selected from thegroup consisting of alumina (Al₂O₃), silica (SiO₂), titanium dioxide(TiO₂), magnesium oxide (MgO), calcium oxide (CaO), a clay andcombinations thereof. In some embodiments, the clay is Bentonite clay,Monterey clay, Kaolin clay, a philosilicate clay or a combinationthereof.

In some embodiments, the particle size of the inert species is less thanor equal to about 300 mesh, less than or equal to about 400 mesh, lessthan or equal to about 500 mesh, or less than or equal to about 600mesh. In some embodiments, the solvent is an aqueous solvent. In someembodiments, the solvent is an organic solvent. In some embodiments, thelayer has a corrosion resistance of at least about 1 year under thecopper acetic acid spray (CASS) test. In some embodiments, during (b),at least about 95% of the at least one elemental metal in the alloyingagent diffuses to or into the substrate. In some embodiments, during(b), the at least one elemental metal is deposited on a surface of thesubstrate via a vapor deposition reaction and diffuses to or into thesubstrate. In some embodiments, the alloying agent is configured todiffuse into the substrate.

In another aspect, the present disclosure provides a method for formingat least one layer comprising at least one elemental metal adjacent to asubstrate, comprising: (a) coating at least a portion of the substratewith a slurry to generate a slurry-coated substrate, wherein the slurrycomprises (i) a solvent, (ii) an alloying agent, wherein the alloyingagent comprises the at least one elemental metal, and wherein thealloying agent is configured to diffuse to or into the substrate, (iii)a halide activator that aids in diffusion of the at least one elementalmetal to the substrate, wherein a molar ratio of a halide of the halideactivator to the at least one elemental metal is at most about 10:1, and(iv) an inert species that aids in suspending the alloying agent in theslurry; and (b) subjecting the slurry-coated substrate to annealingconditions to diffuse the at least one elemental metal to or into thesubstrate, to generate the at least one layer adjacent to the substratecomprising the at least one elemental metal.

In some embodiments, the alloying agent is configured to diffuse intothe substrate. In some embodiments, the layer has a functional componentthat is not connected with the substrate.

In another aspect, the present disclosure provides a method for forminga metal-containing object comprising a metal layer adjacent to asubstrate, comprising: (a) coating at least a portion of the substratewith a slurry comprising an alloying agent having at least one elementalmetal, thereby forming a slurry-coated substrate; and (b) subjecting theslurry-coated substrate to annealing under conditions that aresufficient to form the metal layer adjacent to the substrate, whereinthe metal layer is coupled to the substrate with the aid of a diffusionlayer between the metal layer and the substrate, wherein an amount ofthe alloying agent in the diffusion layer changes with depth at a ratebetween about −0.01% per micrometer and −5.0% per micrometer as measuredby x-ray photoelectron spectroscopy.

In some embodiments, the slurry comprises a solvent, a halide activatorand an inert species that aids in suspending the alloying agent in theslurry. In some embodiments, a molar ratio of a halide of the halideactivator to the at least one elemental metal is at most about 10:1. Insome embodiments, the inert species has a particle size that is lessthan or equal to about 200 mesh. In some embodiments, the substrate is asteel substrate.

In another aspect, the present disclosure provides a method for forminga metal-containing object comprising a metal layer adjacent to asubstrate, comprising: (a) coating at least a portion of the substratewith a slurry comprising an alloying agent having at least one elementalmetal, thereby forming a slurry-coated substrate; and (b) subjecting theslurry-coated substrate to annealing under conditions that aresufficient to form the metal layer adjacent to the substrate, wherein(i) the metal layer has a thickness of less than 500 micrometers, and(ii) in the metal layer, a concentration of the alloying agent is at amaximum in the substrate and decreases by no more than 20 wt. % over adepth of about 50 micrometers or less in the metal layer as measuredwith x-ray photoelectron spectroscopy.

In some embodiments, the metal-containing object is devoid of a materialdiscontinuity between an outer layer of the metal-containing object andthe substrate. In some embodiments, the slurry comprises a solvent, ahalide activator and an inert species that aids in suspending thealloying agent in the slurry. In some embodiments, a molar ratio of ahalide of the halide activator to the at least one elemental metal is atmost about 10:1. In some embodiments, the inert species has a particlesize that is less than or equal to about 200 mesh.

In another aspect, the present disclosure provides a method for forminga metal-containing object comprising a metal layer adjacent to asubstrate, comprising: (a) coating at least a portion of the substratewith a slurry comprising an alloying agent having at least one elementalmetal, thereby forming a slurry-coated substrate; and (b) subjecting theslurry-coated substrate to annealing under conditions that aresufficient to form the metal layer adjacent to the substrate, wherein inthe metal layer, (i) the alloying agent has a concentration of at least10 wt. % at a depth of less than or equal to 30 micrometers from asurface of the substrate, and (ii) the alloying agent has aconcentration of at most 6 wt. % at a depth of greater than 150micrometers from the surface of the substrate. In some embodiments, thealloying agent comprises chromium, nickel, or iron.

In some embodiments, the alloying agent has a concentration of at least15 wt. % at a depth of less than or equal to 50 micrometers from thesurface of the substrate. In some embodiments, the slurry comprises asolvent, a halide activator and an inert species that aids in suspendingthe alloying agent in the slurry. In some embodiments, a molar ratio ofa halide of the halide activator to the at least one elemental metal isat most about 10:1. In some embodiments, the inert species has aparticle size that is less than or equal to about 200 mesh.

Another aspect of the present disclosure provides a computer-readablemedium comprising machine executable code that, upon execution by one ormore computer processors, implements any of the methods above orelsewhere herein.

Another aspect of the present disclosure provides a computer systemcomprising one more ore computer processors and computer memory coupledthereto. The computer memory comprises machine executable code that,upon execution by the one or more computer processors, implements any ofthe methods above or elsewhere herein.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings (also “figure” and “FIG.” herein), of which:

FIG. 1 illustrates a method for forming a layer adjacent to a substrate;

FIG. 2 shows change in viscosity as a result of varying shear rate for aslurry with varying amounts of water;

FIG. 3 shows change in viscosity as a result of varying shear rate forthe slurry with varying amounts of water;

FIG. 4 shows change in viscosity as a result of varying amounts of waterfor the slurry;

FIG. 5 shows change in yield stress as a result of varying amounts ofwater for the slurry;

FIG. 6 is a table that shows the change in viscosity, shear thinningindex, and yield stress as a result of varying amounts of water;

FIG. 7 shows change in viscosity as a result of varying shear rate for aslurry with varying amounts of chromium;

FIG. 8 is a table that shows change in viscosity, shear thinning index(10:1000 and 100:1000), and yield stress for a slurry as a result ofvarying amounts of chromium:

FIG. 9 shows change in viscosity as a result of varying amounts ofchromium for a slurry;

FIG. 10 shows change in yield stress as a result of varying amounts ofchromium for a slurry;

FIG. 11 shows a calculated and an experimental Krieger-Dougherty fit ofchromium loading to viscosity for a slurry;

FIG. 12 is a table that shows change in viscosity, shear thinning index(10:1000 and 100:1000), and yield stress for a slurry as a result ofvarying amounts of aluminum (III) oxide;

FIG. 13 shows change in viscosity for a slurry as a result of varyingamounts of aluminum (III) oxide;

FIG. 14 shows change in yield stress for a slurry as a result of varyingamounts of aluminum (III) oxide;

FIG. 15 shows a calculated and an experimental Krieger-Dougherty fit ofaluminum (III) oxide loading to viscosity for a slurry;

FIG. 16 is a table that shows change in viscosity, shear thinning index(10:1000 and 100:1000), and yield stress for a slurry as a result ofvarying amounts of magnesium chloride;

FIG. 17 shows change in viscosity as a result of varying amounts ofmagnesium chloride for a slurry;

FIG. 18 shows change in yield stress as a result of varying amounts ofmagnesium chloride for a slurry;

FIG. 19 shows change in fluidity with different chloride sources withvaried chloride amounts for a slurry;

FIG. 20 shows change in pH with different chloride sources with varyingamounts of chloride for a slurry;

FIG. 21 shows change in fluidity with varying concentrations ofmagnesium salts for a slurry;

FIG. 22 shows change in pH with various concentrations of magnesiumsalts for a slurry;

FIG. 23 shows change in yield stress with various concentrations andshear rates of magnesium acetate for a slurry;

FIG. 24 shows change in yield stress with various concentrations andshear rates of magnesium sulfate for a slurry;

FIG. 25 shows change in pH, viscosity, and yield stress with variousmagnesium salts across a range of concentrations of salts for a slurry;

FIG. 26 shows change in pH, viscosity, and yield stress with varioussalts across a range of concentrations of salts for a slurry;

FIG. 27 shows change in yield stress as result of various concentrationsof ions for a slurry; and

FIG. 28 shows a computer control system that is programmed or otherwiseconfigured to implement methods provided herein.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and describedherein, it will be obvious to those skilled in the art that suchembodiments are provided by way of example only. Numerous variations,changes, and substitutions may occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments of the invention described herein may beemployed.

The term “slurry,” as used herein, generally refers to a solutioncomprising a liquid phase and a solid phase. The solid phase may be inthe liquid phase. A slurry may have one or more liquid phases and one ormore solid phases.

The term “adjacent” or “adjacent to,” as used herein, generally refersto ‘next to’, ‘adjoining’, ‘in contact with,’ and ‘in proximity to.’ Insome instances adjacent to may be ‘above’ or ‘below.’ A first layeradjacent to a second layer may be in direct contact with the secondlayer, or there may be one or more intervening layers between the firstlayer and the second layer.

The present disclosure provides slurry compositions (or slurries), aswell as systems and methods that employ the slurries to form layersadjacent to substrates. Such layers can include, for example, one ormore of iron, chromium, nickel, silicon, vanadium, titanium, boron,tungsten, aluminum, molybdenum, cobalt, manganese, zirconium, andniobium, oxides thereof, nitrides thereof, sulfides thereof, orcombinations thereof.

The present disclosure provides slurries for use in forming layersadjacent to substrates. A slurry can include various components. Thecomponents of the slurry may include an alloying agent, an activatorsuch as a halide activator, a solvent, and an inert species. Thealloying agent may contain at least one elemental species that isconfigured to diffuse to or into a substrate. Diffusion of the elementalspecies to or into the substrate may be facilitated by the activator.The alloying agent may be dispersed in the solvent with the aid of theinert species. The inert species may have a particle size that is lessthan or equal to about 200 mesh.

The elemental species in the alloying agent can diffuse into or onto thesubstrate according to a concentration gradient. For example, theconcentration of the elemental species in the alloying agent can behighest on the surface of the substrate and can decrease according to agradient along the depth of the substrate. The decrease in concentrationcan be linear, parabolic, Gaussian, or any combination thereof. Theconcentration of the alloying agent in the slurry can be selected basedon the desired thickness of the alloy layer to be formed on thesubstrate. The particle size of the alloying agent may be less thanabout 140 mesh.

The elemental species in the alloying agent can be at transition metal.The elemental species in the alloying agent can be chromium, nickel,aluminum, silicon, vanadium, titanium, boron, tungsten, molybdenum,cobalt, manganese, zirconium, niobium, or combinations thereof.

The alloying agent can comprise carbon. For some applications, thealloying agent contains low levels of carbon. The alloying agent cancomprise a transition metal. The alloying agent can comprise iron,chromium, nickel, silicon, vanadium, titanium, boron, tungsten,aluminum, molybdenum, cobalt, manganese, zirconium, niobium, orcombinations thereof. The alloying agent can be a ferroalloy of atransition metal. The alloying agent can be ferrosilicon (FeSi), ferrochromium (FeCr), chromium (Cr), or combinations thereof. The alloyingagent can be a salt or an oxide. The alloying agent can comprisechromium, nickel, iron, or combinations thereof.

The diffusion of the elemental species in the alloying agent to thesubstrate can be facilitated by an activator. The activator may be ahalide activator. The halide may transport the elemental species in thealloying agent to the surface of the substrate and thus facilitatediffusion of the elemental species to the substrate. For example, thealloying agent may comprise chrome and the halide activator may comprisea chloride. Chloride precursors may transport chrome to the surface ofthe substrate. The molar ratio of a halide of the halide activator tothe elemental species may be at most about 0.0001:1, 0.001:1, 0.1:1,0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1. The molarratio of a halide of the halide activator to the elemental species maybe from about 0.0001:1 to 10:1, or 0.001:1 to 5:1. The molar ratio of ahalide of the halide activator to the elemental species may be at mostabout 10:1.

The diffusion of the elemental species in the alloying agent to thesubstrate can be facilitated by an activator. The activator may be ametal halide activator. The metal halide may transport the elementalspecies in the alloying agent to the surface of the substrate and thusfacilitate diffusion of the elemental species to the substrate. Forexample, the alloying agent may comprise chrome and the metal halideactivator may comprise a chloride. Chloride precursors may transportchrome to the surface of the substrate. The molar ratio of a halide ofthe metal halide activator to the elemental species may be at most about0.0001:1, 0.001:1, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1,9:1, or 10:1. The molar ratio of the halide of the metal halideactivator to the elemental species may be from about 0.0001:1 to 10:1,or 0.001:1 to 5:1.

The activator may also impact the adhesion of the slurry of thesubstrate. In addition, the activator may impact the viscosity of theslurry. Further, the activator may influence the green strength of theslurry-coated substrate. Green strength generally refers to the abilityof a slurry-coated substrate to withstand handling or machining beforethe slurry is completely cured. Accordingly, the activator may beselected based on the desired degree of adhesion of the slurry to thesubstrate, the desired viscosity of the slurry, and the ability of theactivator to increase the green strength of the slurry-coated substrate.In addition, the activator may be selected based on corrosivity of theactivator with respect to the substrate. For example, because some metalhalides can be corrosive to metal substrates and because corrosion maybe undesirable, those metal halides may not selected as activators. Inaddition, some metal halides can be corrosive to components of a rollcoating assembly which applies the slurry to the substrate. Suchcorrosion may be undesirable. Thus, those metal halides may not selectedas activators. The activator may prevent the formation of Kirkendallvoids at the boundary interface of the alloying agent and the substrate.Upon heating, a halide activator may decompose to an oxide. Afterannealing, the activator may act as a binder. In addition, afterannealing, the activator may become inert. The concentration ofactivator can be variable. In some embodiments, the concentration ofactivator can be widely variable. The concentration of activator maydepend on the amount of binders that are added to the slurry.

The activator may be a metal polymer. The activator may include amonovalent metal, a divalent metal, or a trivalent metal. The activatormay be a di-metal halide. Examples of activators include magnesiumchloride (MgCl₂), iron (II) chloride (FeCl₂), calcium chloride (CaCl₂),zirconium (IV) chloride (ZrCl₄), titanium (IV) chloride (TiCl₄), niobium(V) chloride (NbCl₅), titanium (III) chloride (TiCl₃), silicontetrachloride (SiCl₄), vanadium (III) chloride (VCl₃), chromium (III)chloride (CrCl₃), trichlorosilance (SiHCl₃), manganese (II) chloride(MnCl₂), chromium (II) chloride (CrCl₂), cobalt (II) chloride (CoCl₂),copper (II) chloride (CuCl₂), nickel (II) chloride (NiCl₂), vanadium(II) chloride (VCl₂), ammonium chloride (NH₄Cl), sodium chloride (NaCl),potassium chloride (KCl), and combinations thereof.

Magnesium chloride may be a more desirable activator than iron chloride.Magnesium chloride may be cheaper in cost than iron chloride, whilerendering a green strength similar to the green strength rendered byiron chloride. A slurry with magnesium chloride as the activator canexhibit an increase in viscosity. The increased viscosity of the slurrymay not increase the thickness of the dried slurry coating.

The activator may be hydrated. Non-limiting examples of hydratedactivators include iron chloride tetrahydrate (FeCl₂.4H₂O), ironchloride hexahyrdate (FeCl₂.6H₂O), and magnesium chloride hexahydrate(MgCl₂.6H₂O). Magnesium chloride hexahydrate may be a more desirablehydrated activator than iron chloride tetrahydrate. Magnesium chloridehexahydrate may be cheaper in cost than iron chloride tetrahydrate. Inaddition, magnesium chloride hexahydrate may be less corrosive to thesubstrate than iron chrloride tetrahydrate.

Salt additives may be used to obtain desired physical properties of theslurry. Salts may be monovalent or divalent salts. Non-limiting examplesof salt additives include molybdenum (II) sulfide (MoS), manganese (II)sulfide (MnS), iron (II) sulfide (FeS), iron (II) sulfide (FeS₂), iron(III) sulfide (Fe₂S₃), chromium (III) sulfide (Cr₂S₃), copper (II)sulfide (CuS), nickel (II) sulfide (NiS), magnesium (II) sulfide (MgS),magnesium (II) acetate Mg(OAc)₂, and magnesium sulfate MgSO₄. magnesiumchloride (MgCl₂), ammonium chloride (NH₄Cl), iron chloride (FeCl₂),calcium chloride (CaCl₂), sodium chloride (NaCl), sodium acetate(NaOAc), sodium carbonate (Na₂CO₃), lithium chloride (LiCl), lithiumacetate (LiOAc), potassium chloride (KCl), ammonium acetate (NH₄OAc),aluminum acetate (Al(OAc)₃), basic aluminum acetate (Al(OH)(OAc)₂),dibasic aluminum acetate (Al(OH)₂(OAc)).

The slurry may comprise a solvent. Examples of solvents, which can beused alone or as a mixture of solvents, include protic solvents, aproticsolvents, polar solvents, and nonpolar solvents. Non-limiting examplesof solvents include alcohols, such as water, methanol, ethanol,1-propanol, and 2-propanol; aliphatic and aromatic hydrocarbons, such aspentane, hexane, cyclohexane, methylcyclohexane, benzene, toluene andxylene; ethers, such as diethyl ether, diethylene glycol dimethyl ether,tetrahydrofuran and dioxane; halogenated hydrocarbons, such as methylenechloride, chloroform, 1,1,2,2-tetrachloroethane and chlorobenzene;esters and lactones, such as ethyl acetate, butyrolactone andvalerolactone; acid amides and lactams, such as dimethylformamide,dirnethylacetamide and N-tnethylpyrrolidone, and ketones, such asacetone, dibutyl ketone, methyl isobutyl ketone and methoxyacetone.

A slurry may comprise an inert material which aids in dispersing thealloying agent in the solvent. The inert material may be in addition toother components of the slurry. The inert material may aid incontrolling the viscosity of the slurry. For example, the inert materialmay increase viscosity by promoting hydrogen bonding between theactivator and the solvent. In addition, hydrogen bonds may form betweenthe inert material and the activator. Further, the inert material mayprevent the alloying agent from dropping out of suspension. Further, theinert material may prevent “stickers” form forming during the annealingprocess.

Examples of inert material include, without limitation, alumina (Al₂O₃),silica (SiO₂), titanium dioxide (TiO₂), magnesium oxide (MgO), calciumoxide (CaO), bentonite clay, monterey clay, Kaolin clay, philosilicateclay, other clays, and combinations thereof. The inert material mayinclude non-stoichiometric variants of such material.

The boiling point (or boiling temperature) of the solvent may be lessthan or equal to about 200° C., 190° C., 180° C., 170° C., 160° C., 150°C., 140° C., 130° C., 120° C., 110° C., or 100° C.

Chromium particles may be larger in size than other particles in theslurry, and can suspended without high polymer additions.

An organic binder, such as methyl cellulose and polyethylene oxide(PEO), may be added to the slurry. An inorganic binder, such as sodiumsilicate, may be added to the slurry. Organic binders and inorganicbinders may allow reduction of the amount of activator withoutsacrificing green strength and rheological properties.

The particle size of the inert material may be less than about 140 mesh.The particle size of the inert material may be less than or equal toabout 200 mesh, 300 mesh, 400 mesh, 500 mesh, or 600 mesh. The particlesize of the inert material may be less than or equal to about 200 mesh.The particle size may help facilitate removal of the inert materialafter annealing.

The properties of the slurry can be a function of one or more parametersused to form the slurry, maintain the slurry or apply the slurry. Suchproperties can include viscosity, shear thinning index, and yieldstress. Such properties can include Reynolds number, viscosity, pH, andslurry component concentration. Parameters that can influence propertiesof the slurry can include water content, alloying agent identity andcontent, halide activator identity and content, and inert speciesidentity and content, temperature, shear rate and time of mixing.

The present disclosure also provides methods for forming a slurry. Theslurry can be formed by mixing various components of the slurry in amixing chamber (or vessel). In some examples, the slurry is formed bymixing one or more solvents, one or more alloying agents, one or morehalide activators and one or more inert species in the chamber. Suchcomponents may be mixed at the same time or sequentially. For example, asolvent is provided in the chamber and an alloying agent is subsequentlyadded to the chamber.

FIG. 1 illustrates a method of forming a layer adjacent to a substrate.In operation 110, a slurry is prepared from a combination of an alloyingagent, activator, solvent, and inert species, as described elsewhereherein. Such components can be added to a mixing vessel sequentially orsimultaneously. Next, in operation 120, the slurry can be applied fromthe mixing vessel to the substrate. In operation 130, the solvent in theslurry is removed after application by heat or vacuum drying at 90°C.-175° C. for 10-60 seconds. In operation 140, the web or substratematerial is rolled or otherwise prepared for thermal treatment. Themixing sequence is that water is loaded first, the salts are added next,the alumina next, and finally the chromium is added.

During slurry production, the alloying agent, the activator, thesolvent, and the inert species may be mixed together. To preventclumping, dry ingredients may be added to the solvent in controlledamounts. The inert material and alloying agent may be in dry powderform.

The blade used to mix the slurry components may be in the shape of awhisk, a fork, or a paddle. More than one blade may be used to mix theslurry components. Each blade may have different shapes or the sameshape. Dry ingredients may be added to the solvent in controlled amountsto prevent clumping. A high shear rate may be needed to help controlviscosity.

The slurry may exhibit thixotropic behavior, wherein the slurry exhibitsa decreased viscosity when subjected to sheer strain. The shear thinningindex of the slurry can be between about 1 to about 8. In order toachieve the target viscosity, mixing may occur at a high shear rate. Theshear rate can be between about 1 s⁻¹ to about 10,000 s⁻¹ (or Hz). Theshear rate may be about 1 s⁻¹, about 10 s⁻¹, about 100 s⁻¹, about 1,000s⁻¹, about 5,000 s⁻¹, or about 10,000 s⁻¹.

The shear rate of a slurry may be measured on various instruments. Theshear rate may be measured on a TA Instruments DHR-2 rheometer, forexample. The shear rate of a slurry may differ depending on theinstrument used to perform the measurement.

In order to achieve the target or predetermined viscosity, mixing mayoccur for a period of time between 1 minute and 2 hours. Preferably, thetime of mixing is less than 30 minutes. The viscosity of the slurry maydecrease the longer the slurry is mixed. The time of mixing maycorrespond to the length of time needed to homogenize the slurry.

A properly mixed state may be a state where the slurry does not havewater on the surface. A properly mixed state may be a state where thereare no solids on the bottom of the vessel. The slurry may appear to beuniform in color and texture.

The desired viscosity of the slurry can be a viscosity that is suitablefor roll coating. The viscosity of the slurry can be between about 1centipoise (cP) to 5,000,000 cP. The viscosity of the slurry may beabout 1 cP, about 5 cP, about 10 cP, about 50 cP, about 100 cP, about200 cP, about 500 cP, about 1,000 cP, about 10,000 cP, about 100,000 cP,about 1,000,000 cP, or about 5,000,000 cP. The viscosity of the slurrymay be from about 1 cP to 1,000,000 cP, or 100 centipoise cP to 100,000cP. The viscosity of the slurry may depend on shear rate. The viscosityof the slurry may be between about 200 cP to about 10,000 cP, or about600 cP to about 800 cP. The slurry may be between 100 cP and 200 cP inthe application shear window that has shear rates between 1000 s⁻¹ and1000000 s⁻¹. The capillary number of the slurry may be between about0.01 to 10. The yield stress of a slurry may be between about 0 to 1 Pa.

The settling rate of the slurry may be stable to separation orsedimentation for greater than one minute, greater than 15 minutes,greater than 1 hour, greater than 1 day, greater than 1 month, orgreater than 1 year. The settling rate of the slurry may refer to theamount of time the slurry is able to withstand, without mixing, beforesettling occurs, or before the viscosity increases to values that arenot suitable for roll coating. Similarly, the shelf-life of the slurrymay refer to the time that slurry can withstand, without mixing, beforethe slurry thickens to an extent unsuitable for roll coating. Even ifthe slurry settles and thickens, however, the slurry may be remixed toits initial viscosity. The thixotropic index of the slurry can be stablesuch that the slurry does not thicken to unsuitable levels at dead spotsin the pan of a roll coating assembly.

The viscosity of the slurry can be controlled by controlling the extentof hydrogen bonding by adding acid to the slurry during mixing. Inaddition, acid or base may be added to the slurry during mixing in orderto control the pH level of the slurry. The pH level of the slurry can bebetween about 3 to about 12. The pH level of the slurry can be about 5to about 8. The pH level of the slurry can be about 3, about 4, about 5,about 6, about 7, about 8, about 9, about 10, about 11, or about 12. ThepH level of the slurry may change as the slurry settles. Remixing theslurry after the slurry settles may return the pH level of the slurry toinitial pH levels. Varying levels of binder, for example, metal acetate,may be added to a slurry to increase green strength in a slurry.

The fluidity of a slurry can be measured by a tilt test. A tilt test canbe an indication of yield stress and viscosity. As an alternative, arheometer may be used to measure the fluidity of the slurry.

The order in which the ingredients are added may be as follows: first,activator is added to solvent, then inert material is added; then, thealloying agent is added to the mixture. Acid can then be added to themixture in order to control the pH level of the mixture. The method ofaddition may not be required to achieve acceptable slurry properties

The drying time of the slurry can be sufficiently long such that theslurry remains wet during the roll coating process and does not dryuntil after a coating of the slurry is applied to the substrate. Theslurry may not dry at room temperature. The slurry may become dry to thetouch after subjecting the drying zone of a roll coating line to heatfor around ten seconds. The temperature of heat applied may be around120° C.

The specific gravity of the slurry can be about 1 to 10 g/cm³. The greenstrength of the slurry can be such that the slurry is able to withstandroll coating such that the slurry coated substrate is not damaged. Forexample, a dry film of slurry, dried after roll-coating in the dryingoven adjacent to the paint booth, may have a green strength that allowsthe film to survive a force that flexes the film, twenty times, inalternating negative and positive directions, to an arc with a diameterof 20 inches. The green strength of the dry film of slurry may furtherallow the film to pass a tape test with a small amount of powdering. Thetape test may involve contacting a piece of tape with the surface of thecoated material. The tape, once removed from the surface of the coatedmaterial, may be clear enough to allow one to see through any powderthat had adhered to the tape.

After the slurry is prepared, it may be applied to a substrate through,for example, a roll coating process. The substrate may comprise metalsuch as iron, copper, aluminum, or any combination thereof. Thesubstrate may comprise an alloy of metals. The alloy may includeimpurities. The substrate may comprise steel. The substrate may be asteel substrate. The substrate may comprise ceramic. The substrate maybe devoid of free carbon. The substrate can be made from melt phase. Thesubstrate may be in a cold reduced state, in a full hard state (e.g.,not subjected to an annealing step after cold reduction), or in a hotrolled pickled state.

The surface of the substrate may be free of processing oxides. This maybe achieved by conventional pickling. The surface of the substrate canbe reasonably free of organic materials. The surface of the substratemay be reasonably free of organic materials after processing withcommercially available cleaners.

Grain pinning particles may be added, removed, or withheld from thesubstrate during preparation of the substrate in order to control thegrain size of the substrate. For example, grain pinners may be added tothe substrate in order to keep the grain size small and to form pinningpoints. As another example, grain pinners may be withheld from thesubstrate to allow the grains to grow large and to allow for motorlaminations. Grain pinners may be insoluble at the annealingtemperatures.

Examples of grain pinning particles include an intermetallic, a nitride,a carbide, a carbonitride of titanium, aluminum, niobium, vanadium, andcombinations thereof. Non-limiting examples of grain pinning particlesinclude titanium nitride (TiN), titanium carbide (TiC), and aluminumnitride (AlN).

The slurry can be applied to the substrate by roll coating, splitcoating, spin coating, slot coating, curtain coating, slide coating,extrusion coating, painting, spray painting, electrostatic mechanisms,printing (e.g., 2-D printing, 3-D printing, screen printing, patternprinting), chemical vapor deposition, dipping, spraying, combinationsthereof, or through any other suitable method.

The substrate may be pretreated before the slurry is applied to thesubstrate. The substrate may be pretreated by using chemicals to modifythe surface of the substrate in order to improve adhesion of the slurryto the surface of the substrate. Examples of such chemicals includechromates and phosphates.

The slurry can be applied to the substrate by various approaches, suchas roll coating. The roll coating process may begin by providing asubstrate, such as a steel substrate. The substrate may be provided as acoil, coiled mesh, wire, pipe, tube, slab, mesh, dipped formed part,foil, plate, sheet for example, sheet could have a thickness anywherefrom 0.001 inches to 0.100 inches, wire rope, or a rod, or threaded rodwhere a screw pattern has been applied to any length or thickness ofrod. Next, the coiled substrate may be unwound. Next, the unwound steelsubstrate may be provided to roll coaters, which may be coated withslurry. Next, the roll coaters may be activated such that the rollcoaters coat the substrate with the slurry. The substrate may be fedthrough the roll coaters through multiple cycles such that the slurry isapplied to the substrate multiple times. Depending on the properties ofthe slurry, it may be desirable to apply multiple coatings of the slurryto the substrate. Multiple coatings of the slurry can be applied to thesubstrate in order to achieve the desired thickness of the slurry.Different slurry formulations may be used in each of the multiplecoatings. The slurry may be applied in a manner such as to form apattern on the substrate. The pattern may in the form of, for example, agrid, stripes, dots, welding marks, or any combinations thereof.Multiple coatings on the same substrate may form a split coat on asubstrate.

After the slurry is applied to the substrate, the solvent in the slurrymay be removed by heating, vaporization, vacuuming, or any combinationthereof. After the solvent is driven off, the substrate may be recoiled.Next, the coiled slurry coated substrate may be annealed.

The slurry coated, coiled substrate may be placed in a retort andsubjected to a controlled atmosphere during heat treatment. Removal ofwater may be necessary. Pulling vacuum to force hydrogen between wrapsmay be necessary. The annealing process may be via tight coil or loosecoil annealing. Annealing the slurry coated substrate can allow theelemental species in the slurry to diffuse into or through thesubstrate. Up to about 100% wt of the elemental species may diffuse intoor through the substrate upon annealing. Certain process conditions mayafford only 1-5% of the elemental species diffusing from the coatinginto the substrate. Diffusion of the elemental species to the substratemay be aided by an activator in the slurry. To prevent loss of theactivator during annealing, hydrochloric acid may be added to theannealing gas. Minimizing the partial pressure of activator in thereactor at high temperatures may maintain a low deposition rate that isessential for minimizing or stopping the formation of Kirkendall pores.Adding too much of an acidic activator may also cause corrosion of thecoating equipment or the substrate. The annealing process may be acontinuous annealing process.

The slurry-coated substrate may be incubated or stored under vacuum oratmospheric conditions prior to annealing. This occurs prior toannealing and may be useful in removing residual contaminants from thecoating, for example, solvent or binder leftover from the coatingprocess. The incubation period may last between about 10 seconds toabout 5 minutes or may be more than about 5 minutes. The incubationperiod may be the time between coating and annealing, and may be thelength of time needed to transport the coated article to the heattreatment facility or equipment. For example, the incubation period maylast for about 10 seconds, about 30 seconds, about 1 minute, about 2minutes, about 3 minutes, about 4 minutes, or about 5 minutes. Theincubation temperature may range from about 50° C. to about 300° C. Forexample, the incubation temperature may be more than about 50° C., about75° C., about 100° C., about 125° C., about 150° C., about 175° C.,about 200° C., about 225° C., about 250° C., about 275° C., or about300° C. After incubating, and prior to annealing, the dry film of slurryon the substrate can be maintained under vacuum conditions. The coatingmay be dry to the touch immediately following the drying step after theroll-coating process. Absorbed water or other contaminants may bepresent with the coating anytime between roll coating and annealing.

The annealing temperature may be about 800° C., 900° C., 1000° C., 1100°C., 1200° C., or 1300° C. The heating temperature during annealing canbe about 800° C. to about 1300° C., such as about 900° C. to about 1000°C. The annealing atmosphere, may comprise hydrogen, nitrogen, argon. Theannealing atmosphere can be a vacuum.

The total annealing time, including heating, can range from about 5hours to about 200 hours. For example, the total annealing time can bemore than about 5 hours, about 20 hours, about 40 hours, about 60 hours,about 80 hours, about 100 hours, about 120 hours, about 140 hours, about160 hours, about 180 hours, or about 200 hours. The maximum temperatureduring the annealing process may be reached in about 1 hour to 100hours. For example, the maximum temperature during the annealing processmay be reached in about 1 hour, 10 hours, 20 hours, 30 hours, 40 hours,50 hours, 60 hours, 70 hours, 80 hours, 90 hours, or 100 hours.

Large articles may have hot spots or cold spots during thermaltreatment, where an article might be coated evenly but heated unevenly.Hot spots or cold spots may be denoted to control the diffusion ofalloying element into the article as uniformly as possible.

A residue may remain on the substrate after the annealing process. Theactivator in the slurry may be consumed or removed (e.g., deposited onthe walls of the retort), and the concentration of the alloying agent isreduced due to its diffusion onto and/or into the substrate. However,after annealing, other residue in the form of, e.g., a powder, mayremain on the substrate. The residue may comprise the inert materialfrom the slurry. This residue may be removed prior to further processing(e.g., temper rolling). The reaction can be purged with HCl gas to haltthe reaction. The purging with HCl gas can allow for the formation of aflat profile.

After annealing, a layer may be formed on the substrate. The layer mayhave at least one elemental species. The layer may be an outer layerwith at least one elemental species having a concentration that variesby less than about 20 wt. %, about 15 wt. %, about 10 wt. %, about 5 wt.%, about 4 wt. %, about 3 wt. %, about 2 wt. %, about 1 wt. %, or about0.5 wt. % in the outer layer. The substrate may comprise a bonding layeradjacent the outer layer. The elemental species may have a concentrationthat decrease to less than about 1.0 wt % in the boding layer. The layermay comprise stainless steel. The substrate can be substantially free ofKirkendall voids after annealing. The layer can impart characteristicson the substrate which the substrate did not previously contain. Forexample, the layer may make the substrate harder, more wear resistant,more aesthetically pleasing, more electrically resistive, lesselectrically resistive, more thermally conductive, or less thermallyconductive. In addition, the layer may cause the speed of sound in thesubstrate to be faster or slower.

The present disclosure provides objects (e.g., sheets, tubes or wires)coated with one or metal layers. A metal layer may include one or moremetals. In some cases, a substrate may be coated with a metal layer. Thecoating may comprise an alloying agent having at least one elementalmetal. A slurry-coated substrate may be formed when a substrate iscoated with a slurry comprising an alloying agent having at least oneelemental metal. A substrate that has been coated with an alloying agentmay be subjected to annealing conditions. The metal layer may be coupledto a substrate with the aid of a diffusion layer between the metal layerand the substrate.

The amount of an alloying agent in a diffusion layer may change withdepth. The amount of an alloying agent in a diffusion layer may have achange with depth at a certain rate, such as about −0.01% permicrometer, about −0.01% per micrometer, about −0.01% per micrometer,about −0.05% per micrometer, about −0.1% per micrometer, about −0.5% permicrometer, about −1.0% per micrometer, about −3.0% per micrometer,about −5.0% per micrometer, about −7.0% per micrometer, or about −9.0%per micrometer. The amount of an alloying agent in a diffusion layer mayhave a change with depth from about −0.01% per micrometer to −5.0% permicrometer, or from about −0.01% per micrometer to −3.0% per micrometer.X-ray photoelectron spectroscopy may be used to measure such change inamount (or concentration) with depth.

An alloying agent may have a concentration of at least about 5 wt % at adepth of less than or equal to 100 micrometers, about 10 wt % at a depthof less than or equal to 30 micrometers, about 15 wt % at a depth ofless than or equal to 50 micrometers, or about 15 wt % at a depth ofless than or equal to 10 micrometers from the surface of the substrate.

A concentration of an alloying agent in a metal layer may be at mostabout 20 wt. % over a depth of about greater than 100 micrometers, 15wt. % over a depth of about greater than 110 micrometers, about 10 wt. %over a depth of about 125 micrometers, 8 wt. % over a depth of aboutgreater than 140 micrometers, or about 6 wt. % over a depth of about 150micrometers from the surface of the substrate.

A concentration of an alloying agent in a metal layer may decrease overa certain depth as a result of annealing of a metal layer on asubstrate. A concentration of an alloying agent in a metal layer maydecrease by no more than about 50 wt. % over a depth of about 100micrometers, about 40 wt. % over a depth of about 90 micrometers, about30 wt. % over a depth of about 70 micrometers, about 25 wt. % over adepth of about 60 micrometers, or about 20 wt. % over a depth of about50 micrometers.

A metal layer that is coated onto a substrate may have a certainthickness after the metal layer is annealed onto the substrate. A metallayer that is coated onto a substrate may have a thickness less thanabout 1 millimeter, about 900 micrometers, about 800 micrometers, about700 micrometers, about 600 micrometers, about 500 micrometers, 400micrometers, about 300 micrometers, about 200 micrometers, or about 100micrometers.

Other properties of substrates coated with metal layers may be asdescribed in, for example, U.S. Patent Publication No. 2013/0171471;U.S. Patent Publication No. 2013/0309410; U.S. Patent Publication No.2013/0252022; U.S. Patent Publication No. 2015/0167131; and U.S. PatentPublication No. 2015/0345041, each of which is incorporated herein byreference in its entirety.

Another aspect of the present disclosure is a method for forming ametal-containing object comprising a metal layer adjacent to asubstrate. The metal-containing object may be devoid of a materialdiscontinuity between an outer layer of the metal-containing object andthe substrate.

Computer Control Systems

The present disclosure provides computer control systems that areprogrammed to implement methods of the disclosure. FIG. 28 shows acomputer control system 2801 that is programmed or otherwise configuredto produce the slurry and/or apply a coating of the slurry to asubstrate. The computer control system 2801 can regulate various aspectsof the methods of the present disclosure, such as, for example, methodsof producing the slurry and methods of applying a coating of the slurryto the substrate. The computer control system 2801 can be implemented onan electronic device of a user or a computer system that is remotelylocated with respect to the electronic device. The electronic device canbe a mobile electronic device.

The computer system 2801 includes a central processing unit (CPU, also“processor” and “computer processor” herein) 2805, which can be a singlecore or multi core processor, or a plurality of processors for parallelprocessing. The computer control system 2801 also includes memory ormemory location 2810 (e.g., random-access memory, read-only memory,flash memory), electronic storage unit 2815 (e.g., hard disk),communication interface 2820 (e.g., network adapter) for communicatingwith one or more other systems, and peripheral devices 2825, such ascache, other memory, data storage and/or electronic display adapters.The memory 2810, storage unit 2815, interface 2820 and peripheraldevices 2825 are in communication with the CPU 2805 through acommunication bus (solid lines), such as a motherboard. The storage unit2815 can be a data storage unit (or data repository) for storing data.The computer control system 2801 can be operatively coupled to acomputer network (“network”) 2830 with the aid of the communicationinterface 2820. The network 2830 can be the Internet, an internet and/orextranet, or an intranet and/or extranet that is in communication withthe Internet. The network 2830 in some cases is a telecommunicationand/or data network. The network 2830 can include one or more computerservers, which can enable distributed computing, such as cloudcomputing. The network 2830, in some cases with the aid of the computersystem 2801, can implement a peer-to-peer network, which may enabledevices coupled to the computer system 2801 to behave as a client or aserver.

The CPU 2805 can execute a sequence of machine-readable instructions,which can be embodied in a program or software. The instructions may bestored in a memory location, such as the memory 2810. The instructionscan be directed to the CPU 2805, which can subsequently program orotherwise configure the CPU 2805 to implement methods of the presentdisclosure. Examples of operations performed by the CPU 2805 can includefetch, decode, execute, and writeback.

The CPU 2805 can be part of a circuit, such as an integrated circuit.One or more other components of the system 2801 can be included in thecircuit. In some cases, the circuit is an application specificintegrated circuit (ASIC).

The storage unit 2815 can store files, such as drivers, libraries andsaved programs. The storage unit 2815 can store user data, e.g., userpreferences and user programs. The computer system 2801 in some casescan include one or more additional data storage units that are externalto the computer system 2801, such as located on a remote server that isin communication with the computer system 2801 through an intranet orthe Internet.

The computer system 2801 can communicate with one or more remotecomputer systems through the network 2830. For instance, the computersystem 2801 can communicate with a remote computer system of a user(e.g., a user controlling the manufacture of a slurry coated substrate).Examples of remote computer systems include personal computers (e.g.,portable PC), slate or tablet PC's (e.g., Apple® iPad, Samsung® GalaxyTab), telephones, Smart phones (e.g., Apple® iPhone, Android-enableddevice, Blackberry®), or personal digital assistants. The user canaccess the computer system 2801 via the network 2830.

Methods as described herein can be implemented by way of machine (e.g.,computer processor) executable code stored on an electronic storagelocation of the computer system 2801, such as, for example, on thememory 2810 or electronic storage unit 2815. The machine executable ormachine readable code can be provided in the form of software. Duringuse, the code can be executed by the processor 2805. In some cases, thecode can be retrieved from the storage unit 2815 and stored on thememory 2810 for ready access by the processor 2805. In some situations,the electronic storage unit 2815 can be precluded, andmachine-executable instructions are stored on memory 2810.

The code can be pre-compiled and configured for use with a machinehaving a processer adapted to execute the code, or can be compiledduring runtime. The code can be supplied in a programming language thatcan be selected to enable the code to execute in a pre-compiled oras-compiled fashion.

Aspects of the systems and methods provided herein, such as the computersystem 2801, can be embodied in programming. Various aspects of thetechnology may be thought of as “products” or “articles of manufacture”typically in the form of machine (or processor) executable code and/orassociated data that is carried on or embodied in a type of machinereadable medium. Machine-executable code can be stored on an electronicstorage unit, such as memory (e.g., read-only memory, random-accessmemory, flash memory) or a hard disk. “Storage” type media can includeany or all of the tangible memory of the computers, processors or thelike, or associated modules thereof, such as various semiconductormemories, tape drives, disk drives and the like, which may providenon-transitory storage at any time for the software programming. All orportions of the software may at times be communicated through theInternet or various other telecommunication networks. Suchcommunications, for example, may enable loading of the software from onecomputer or processor into another, for example, from a managementserver or host computer into the computer platform of an applicationserver. Thus, another type of media that may bear the software elementsincludes optical, electrical and electromagnetic waves, such as usedacross physical interfaces between local devices, through wired andoptical landline networks and over various air-links. The physicalelements that carry such waves, such as wired or wireless links, opticallinks or the like, also may be considered as media bearing the software.As used herein, unless restricted to non-transitory, tangible “storage”media, terms such as computer or machine “readable medium” refer to anymedium that participates in providing instructions to a processor forexecution.

Hence, a machine readable medium, such as computer-executable code, maytake many forms, including but not limited to, a tangible storagemedium, a carrier wave medium or physical transmission medium.Non-volatile storage media include, for example, optical or magneticdisks, such as any of the storage devices in any computer(s) or thelike, such as may be used to implement the databases, etc. shown in thedrawings. Volatile storage media include dynamic memory, such as mainmemory of such a computer platform. Tangible transmission media includecoaxial cables; copper wire and fiber optics, including the wires thatcomprise a bus within a computer system. Carrier-wave transmission mediamay take the form of electric or electromagnetic signals, or acoustic orlight waves such as those generated during radio frequency (RF) andinfrared (IR) data communications. Common forms of computer-readablemedia therefore include for example: a floppy disk, a flexible disk,hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD orDVD-ROM, any other optical medium, punch cards paper tape, any otherphysical storage medium with patterns of holes, a RAM, a ROM, a PROM andEPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wavetransporting data or instructions, cables or links transporting such acarrier wave, or any other medium from which a computer may readprogramming code and/or data. Many of these forms of computer readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processor for execution.

The computer system 2801 can include or be in communication with anelectronic display 2835 that comprises a user interface (UI) 2840 forproviding, for example, parameters for producing the slurry and/orapplying the slurry to a substrate. Examples of UI's include, withoutlimitation, a graphical user interface (GUI) and web-based userinterface.

Methods and systems of the present disclosure can be implemented by wayof one or more algorithms. An algorithm can be implemented by way ofsoftware upon execution by the central processing unit 2805. Thealgorithm can, for example, regulate the mixing shear rate of theslurry, the amount of each ingredient added to the slurry mixture, andthe order in which the ingredients are added to the slurry mixture. Asanother example, the algorithm can regulate the speed at which theslurry is applied to the substrate and the number of coatings of slurryapplied to the substrate.

EXAMPLES Example 1

In an example, a slurry is formed by mixing water, an alloying agent, ahalide activator and an inert species in a mixing chamber, the preferredspecies being chromium, magnesium chloride hexahydrate, and alumina.These components are added to the mixing chamber while mixing aresulting solution. The shear rate of mixing can be varied, andproperties such as viscosity and yield stress are recorded, listed, andshown in FIG. 2-FIG. 6.

The amount of water added to the slurry is varied to form a number ofslurries, and the resulting effect on properties of the slurries isrecorded. Next, the slurry is applied to a carbon steel substrate via aroll coating process. The slurry is then annealed at 200° C. for 2hours. The slurry is then dried to completeness between about 2 hours toabout 100 hours or longer. The atmosphere near the chromized article'ssurface may be below −20° F. dew point.

Example 2

In another example, a slurry is formed by mixing various components ofthe slurry in a mixing chamber. The slurry is formed by mixing asolvent, such as water, an alloying agent, such as iron silicate, ahalide activator, such as iron chloride, and an inert species, such aschromium, in a high shear mixer. Shear rate is varied, and propertiessuch as viscosity and yield stress are recorded and listed in FIG.7-FIG. 10. The amount of chromium added to the slurry is varied to forma number of slurries, and the resulting effect on properties of theslurries is recorded. The slurry is then applied to a substrate rollcoating. The slurry is dried on the substrate that brings the substrateto a temperature between 70° C. to 120° C. for a time between 20 secondsand 120 seconds. The excess slurry is removed before subsequentprocessing.

Example 3

In another example, a slurry is formed by mixing various components ofthe slurry in a mixing chamber. The slurry is formed by mixing asolvent, such as water, an alloying agent, such as iron silicate, ahalide activator, such as iron chloride, and an inert species, such asaluminum (III) oxide, in a chamber. Shear rate is varied, and propertiessuch as viscosity and yield stress are recorded and listed in FIG.12-FIG. 14. The amount of alumina added to the slurry is varied to forma number of slurries, and the resulting effect on properties of theslurries is recorded. The slurry is then applied to a substrate via asingle step process. The slurry is dried on the substrate that bringsthe substrate to a temperature between 70° C. to 120° C. for a timebetween 20 seconds and 120 seconds. The excess slurry is removed beforesubsequent processing.

Example 4

In another example, a slurry is formed by mixing various components ofthe slurry in a mixing chamber. The slurry is formed by mixing asolvent, such as water, an alloying agent, such as ferro-silicon, ahalide activator, such as iron chloride, and an inert species, such asalumina, in a chamber. Shear rate is varied, and properties such asviscosity, yield stress, fluidity, and pH are recorded and listed inFIG. 16-FIG. 18, FIG. 21 and FIG. 22. The amount of magnesium chlorideadded to the slurry is varied to form a number of slurries, and theresulting effect on properties of the slurries is recorded.

Example 5

In another example, a slurry is formed, comprising 15 g chromium, 5.25 galumina, 0.25 g MgCl₂.6H₂O, and water in amounts from 4.2 g to 5.4 g in0.2 g increments. These components are added to the mixing chamber whilemixing a resulting solution. The shear rate of mixing can be varied, andproperties such as viscosity and yield stress are recorded, listed, andshown in FIG. 2-FIG. 6.

FIGS. 2 and 3 illustrate examples in which varying amounts of water canaffect the viscosity of a slurry. The figures show various curves A-G inwhich viscosity may decrease with increasing shear rate. The curves arein order of increasing water content. For example, curve A has a watercontent of 4.2 grams (g) and curve G has a water content of 5.4 g.Generally, increasing the shear rate can decrease the viscosity of theslurry. Increasing the amount of water can decrease the viscosity of theslurry. In some cases, the slurry can have a viscosity from about 1×10⁻²pascal (Pa) second to 100 Pa second at a shear rate from about 0.01 s⁻¹to 1,000 s⁻¹. For example, the slurry can have a viscosity of 10 Pasecond at 4 s⁻¹ or 1×10⁻² Pa second at 7400 s⁻¹.

The viscosity of the slurry can be a function of the weight of water inthe slurry. FIG. 4 illustrates change in viscosity at a fixed shear rate(1000 s⁻¹) as a result of varying amounts of water of a slurry. Anincrease of weight of water in the slurry can decrease the viscosity ofthe slurry. The decrease may be linear. In some examples, the viscosityof the slurry at a shear rate of 1000 s⁻¹ can be from about 140centipoise (cP) at a weight of water in the slurry of about 4.2 g to 60cP at a water weight of 5.4 g.

The yield stress of the slurry can be a function of the weight of waterin the slurry. FIG. 5 illustrates change in yield stress as a result ofvarying amounts of water of a slurry. An increase of weight of water inthe slurry can decrease the yield stress of the slurry. The decrease maybe linear. In some examples, the yield stress of the slurry can be about70 pascal (Pa) at a weight of water in the slurry of about 4.2 g toabout 30 Pa at a water weight of 5.4 g.

FIG. 6 illustrates change in viscosity, shear thinning index, and yieldstress as a result of varying amounts of water. Generally, increasingthe amount of water in the slurry can decrease the viscosity of theslurry. The decrease may be linear. In some examples, the viscosity ofthe slurry at a shear rate of 1000 s⁻¹ can be from about 136 centipoise(cP) at a weight of water in the slurry of about 4.2 g to 61 cP at awater weight of 5.4 g. Generally, increasing the amount of water in aslurry can decrease the shear thinning index of the slurry. The decreasemay be linear. In some examples, the shear thinning index can be fromabout 6.1 (100:1000 s⁻¹) at a weight of water in the slurry of about 4.2g to about 5.8 at a water weight of 5.4 g. An increase of weight ofwater in a slurry can decrease the yield stress of the slurry. Thedecrease may be linear. In some examples, the yield stress of the slurrycan be about 71 pascal (Pa) at a weight of water in the slurry of about4.2 g to about 30 Pa at a water weight of 5.4 g.

Example 6

The viscosity of a slurry can be a function of the weight of an alloyingagent in the slurry, such as chromium. FIG. 7 illustrates an example inwhich varying amounts of chromium can affect the viscosity of a slurry.A slurry is formed, comprising 5 g water, 5.25 g alumina, 0.25 gMgCl₂.6H₂O, and chromium in amounts between 1 g and 35 g. The figureshows various curves A-J in which viscosity may decrease with increasingshear rate. The curves are in order of increasing chromium content. Forexample, curve A has a chromium content of 1.0 grams (g) and curve J hasa water content of 35.0 g. Generally, increasing the shear rate candecrease the viscosity of the slurry. Increasing the amount of chromiumcan decrease the viscosity of the slurry. In some cases, the slurry canhave a viscosity from about 1×10⁻² pascal (Pa) second to 100 Pa secondat a shear rate from about 0.01 s⁻¹ to 1,000 s⁻¹. For example, theslurry can have a viscosity of 1,000 Pa second at 0.01 s⁻¹. For example,the slurry can have a viscosity of 1×10⁻² Pa second at 1,000 s⁻¹.

The viscosity, shear thinning index, and yield stress of the slurry canbe a function of the weight of an alloying agent in the slurry, such aschromium. FIG. 8 illustrates change in viscosity, shear thinning index,and yield stress as a result of varying amounts of chromium. Generally,increasing the amount of chromium in a slurry can increase the viscosityof the slurry. The increase may be exponential. In some examples, theviscosity of the slurry at a shear rate of 1000 s⁻¹ can be from about 26centipoise (cP) at a weight of chromium in the slurry of about 1.0 g to442 cP at a chromium weight of 35.0 g. Generally, increasing the amountof chromium in a slurry can decrease the shear thinning index of theslurry. The decrease may be linear. In some examples, the shear thinningindex can be from about 42 (10:1000 s⁻¹) at a weight of chromium in theslurry of about 1.0 g to about 6 at a chromium weight of 35.0 g. In someexamples, the shear thinning index can be from about 5.5 (100:1000 s⁻¹)at a weight of chromium in the slurry of about 1.0 g to about 3.0 at achromium weight of 35.0 g. An increase of weight of chromium in a slurrycan increase the yield stress of the slurry. The increase may be linear.In some examples, the yield stress of the slurry can be about 10 pascal(Pa) at a weight of chromium in the slurry of about 1.0 g to about 104Pa at a chromium weight of 35.0 g.

The viscosity of the slurry can be a function of the weight of analloying agent in the slurry, such as chromium. FIG. 9 illustrateschange in viscosity at a fixed shear rate (1000 s⁻¹) as a result ofvarying amounts of chromium of the slurry. An increase of chromium in aslurry can increase the viscosity of the slurry. The increase may beexponential. In some examples, the viscosity of the slurry at a shearrate of 1000 s⁻¹ can be from about 25 centipoise (cP) at a weight ofchromium in the slurry of about 1.0 g to about 450 cP at a chromiumweight of 35.0 g.

The yield stress of the slurry can be a function of the weight ofalloying agent (e.g., chromium) in the slurry. FIG. 10 illustrateschange in yield stress as a result of varying amounts of chromium in theslurry. An increase of chromium in the slurry can increase the yield ofthe slurry. The increase may be linear. In some examples, the yieldstress of the slurry can be about 10 pascal (Pa) at a weight of chromiumin the slurry of about 1.0 g to about 100 Pa at a chromium weight of35.0 g.

FIG. 11 illustrates experimental data and a calculated Krieger-Doughertyfit of chromium loading to viscosity for a slurry. The experimental dataand calculated Krieger-Dougherty fit of chromium loading to viscosityfor a slurry may correspond well. An increase of chromium in a slurrycan increase the viscosity of the slurry. The increase may beexponential.

Example 7

Various properties of a slurry can be selected or tailored as desired.Such properties can include viscosity, shear thinning index, and yieldstress. In some examples, these properties can change with aluminacontent.

In another example, a slurry is formed, comprising about 5 g water, 15 gchromium, 0.25 g MgCl₂.H₂O, and alumina in amounts from 4.5 g to 7.5 gin 0.5 g increments. FIG. 12 illustrates change in viscosity, shearthinning index, and yield stress as a result of varying amounts ofalumina. Generally, increasing the amount of alumina in a slurry canincrease the viscosity of the slurry. The increase may be exponential.In some examples, the viscosity of the slurry at a shear rate of 1000s⁻¹ can be from about 57 centipoise (cP) at a weight of alumina in theslurry of about 4.5 g to 203 cP at a chromium weight of 7.5 g.Generally, increasing the amount of alumina in a slurry can decrease theshear thinning index of the slurry. In some examples, the shear thinningindex can be from about 42 (10:1000 s⁻¹) at a weight of alumina in theslurry of about 4.5 g to about 14 at an alumina weight of 7.5 g. In someexamples, the shear thinning index can be from about 5.6 (100:1000 s⁻¹)at a weight of alumina in the slurry of about 4.5 g to about 5.9 at analumina weight of 7.5 g. An increase of weight of alumina in a slurrycan increase the yield stress of the slurry. In some examples, the yieldstress of the slurry can be about 26 pascal (Pa) at a weight of aluminain the slurry of about 4.5 g to about 104 Pa at an alumina weight of 7.5g.

The viscosity of the slurry can be a function of the weight of an inert(e.g. alumina) in the slurry. FIG. 13 illustrates change in viscosity ata fixed shear rate (1000 s⁻¹) as a result of varying amounts of aluminaof a slurry. An increase of alumina in a slurry can increase theviscosity of the slurry. The increase may be exponential. In someexamples, the viscosity of the slurry at a shear rate of 1000 s⁻¹ can befrom about 50 centipoise (cP) at a weight of alumina in the slurry ofabout 4.5 g to about 200 cP at an alumina weight of 7.5 g. Though notwishing to be bound by mechanistic theory, higher amounts of aluminum(III) oxide in a slurry may interact chemically with the slurry tochange structural or physical properties.

The yield stress of the slurry can be a function of the weight of aninert (e.g. aluminum oxide) in the slurry. FIG. 14 illustrates change inyield stress as a result of varying amounts of aluminum (III) oxide of aslurry. An increase of aluminum (III) oxide in a slurry can increase theyield of the slurry. The increase may be exponential. In some examples,the yield stress of the slurry can be about 25 pascal (Pa) at a weightof alumina in the slurry of about 4.5 g to about 100 Pa at an aluminaweight of 7.5 g.

FIG. 15 illustrates a calculated and an experimental Krieger-Doughertyfit of aluminum (III) oxide loading to viscosity for a slurry. Theexperimental data and calculated Krieger-Dougherty fit of aluminum (III)oxide loading to viscosity for a slurry may correspond well. An increaseof aluminum in a slurry can increase the viscosity of the slurry. Theincrease may be linear or exponential.

Example 9

Slurry properties can change with the content of an activator (e.g.magnesium chloride). FIG. 16 illustrates change in viscosity, shearthinning index, and yield stress as a result of varying amounts ofmagnesium chloride. Generally, increasing the amount of magnesiumchloride in a slurry can decrease the viscosity of the slurry. Thedecrease may be exponential or logarithmic. In some examples, theviscosity of the slurry at a shear rate of 1000 s⁻¹ can be from about 93centipoise (cP) at a weight of magnesium chloride in the slurry of about0.1 g to 35 cP at a magnesium chloride weight of 4 g. Generally,increasing the amount of magnesium chloride in a slurry can change theshear thinning index of the slurry. In some examples, the shear thinningindex can be from about 16 (10:1000 s⁻¹) at a weight of alumina in theslurry of about 0.1 g to about 42 at a magnesium chloride weight of 0.8g to about 16 at a magnesium chloride weight of 4 g. In some examples,the shear thinning index can be from about 5.8 (100:1000 s⁻¹) at aweight of magnesium chloride in the slurry of about 0.1 g to about 3.1at a magnesium chloride weight of 4 g. An increase of weight ofmagnesium chloride in a slurry can decrease the yield stress of theslurry. The decrease may be exponential. In some examples, the yieldstress of the slurry can be about 47 pascal (Pa) at a weight ofmagnesium chloride in the slurry of about 0.1 g to about 4 Pa at amagnesium chloride weight of 4 g.

The viscosity of the slurry can be a function of the weight of anactivator (e.g. magnesium chloride) in the slurry. FIG. 18 illustrateschange in viscosity at a fixed shear rate (1000 s⁻¹) as a result ofvarying amounts of magnesium chloride of a slurry. An increase ofmagnesium chloride in a slurry can decrease the viscosity of the slurry.The decrease may be exponential. In some examples, the viscosity of theslurry at a shear rate of 1000 s⁻¹ can be from about 90 centipoise (cP)at a weight of magnesium chloride in the slurry of about 0.1 g to about40 cP at a magnesium chloride weight of 4 g.

Physical properties of the slurry can be a function of the amount ofactivator in the slurry. For example, the yield stress of the slurry canbe a function of the weight of magnesium chloride in the slurry. FIG. 18illustrates change in yield stress as a result of varying amounts ofmagnesium chloride of a slurry. An increase magnesium chloride in aslurry can decrease the yield of the slurry. The decrease may beexponential. In some examples, the yield stress of the slurry can beabout 50 pascal (Pa) at a weight of magnesium chloride in the slurry ofabout 0.1 g to about 5 Pa at a magnesium chloride weight of 4 g.

FIG. 19 illustrates the results of a tilt test, where change in fluiditywith different chloride sources with varied chloride amounts for aslurry is demonstrated. Higher amounts of magnesium chloride, ironchloride, and calcium chloride in a slurry may correspond with increasedfluidity of the slurry. In some examples, 0.1 moles of chloride frommagnesium chloride, iron chloride, and calcium chloride can correspondto a fluidity of the slurry of about 10 graduated cylinder units. Insome examples, higher amounts of ammonium chloride in a slurry may havelittle change on the fluidity of the slurry, and 0.1 moles of chloridefrom ammonium chloride can correspond to a fluidity of the slurry ofabout 0.5 grad cyl units on a ten milliliter cylinder.

The pH of a slurry may change as a function of the chloride source usedin the slurry. FIG. 20 illustrates change in pH with different chloridesources with varying amounts of chloride for a slurry. Higher amounts ofmagnesium chloride, ammonium chloride, iron chloride, and calciumchloride in a slurry may correspond with a slight decrease in pH of theslurry. In some examples, 0.1 moles of chloride from magnesium chloride,ammonium chloride, iron chloride, and calcium chloride may correspond toa pH of about 5, 7, 2, and 4, respectively.

Example 10

Physical properties of the slurry may be influence by the identity andcontent of salts that can be added to the slurry. FIG. 21 illustrateschange in fluidity with varying concentrations of magnesium salts for aslurry. Tilt tests of slurries were performed. Generally, higher amountsof magnesium salts, such as magnesium chloride, magnesium acetate, andmagnesium sulfate, in a slurry may correspond with an increase influidity of the slurry. In some examples, 0.02 moles of magnesium inmagnesium sulfate and magnesium acetate can correspond to a fluidity ofthe slurry of about 6 grad cyl units. In some examples, 0.02 moles ofmagnesium in magnesium chloride can correspond to a fluidity of theslurry of about 4 grad cyl units.

FIG. 22 illustrates change in pH with various concentrations ofmagnesium salts for a slurry. Generally, higher amounts of magnesiumsalts, such as magnesium chloride, magnesium acetate, and magnesiumsulfate, in a slurry may correspond with a slight decrease in pH of theslurry. The decrease may be exponential. In some examples, 0.02 moles ofmagnesium from magnesium chloride, magnesium acetate and magnesiumsulfate may correspond to a pH of about 7, 7.5, and 6, respectively.

FIG. 23 illustrates change in yield stress with various concentrationsand shear rates of magnesium acetate for a slurry. The slurry comprises15 g chromium, 7.5 g alumina, 5.05 g water, and 0.01 g to 10 g ofMg(OAc)₂.4H₂O. Generally, increasing the shear rate can decrease theyield stress of the slurry. Increasing the amount of magnesium acetatecan correspond with a decrease in the yield stress of the slurry untilthe solubility limit is reached. Monotonic thinning behavior may beobserved as more salt is dissolved until the solubility limit isreached. In some examples, the amounts of magnesium acetate in a slurryis about 0.01 g, 1 g, 2 g, 4 g, or 10 g.

FIG. 24 illustrates change in yield stress with various concentrationsand shear rates of magnesium sulfate for a slurry comprising 15 gchromium, 7.5 g alumina, 5.05 g water, and 0.01 g to 10 g ofMg(OAc)₂.7H₂O. A decrease in viscosity as a function of increasing saltis observed. Monotonic thinning behavior may be observed as more salt isdissolved until the solubility limit is reached. 0.0018 g to 0.8000 gMgSO₄ per gram of water in the slurry was used to prepare samples 6-9.

FIG. 25 illustrates change in pH, viscosity, and yield stress withvarious magnesium salts across a range of concentrations of salts for aslurry.

Properties of the slurry, such as pH, viscosity, and yield stress) maybe influence by the identity and content of salts that can be added tothe slurry. FIG. 26 illustrates change in pH, viscosity, and yieldstress with various salts across a range of concentrations of salts fora slurry. Though not wishing to be bound by mechanistic theory, cationicvalency might directly influence slurry rheology and ionic strength ofsalts may not predict slurry rheology. Monovalent acetate salts may bebeneficial for target green strength properties. Monovalent salt slurryviscosities might be time dependent at low concentrations. Though notwishing to be bound by mechanistic theory, dibasic aluminum acetate maybe added to benefit and remove apparent yield stress in high aluminaloading slurries and may demonstrate good cohesion but poor adhesion ingreen strength tests. The slurry comprises 15 g chromium, 7.5 g alumina,5.05 g water, and a varying amount of salt, wherein, #1 refers to 0.1mmol of salt, #2 refers to 5 mmol of salt, #3 refers to 9 mmol of salt,#4 refers to 20 mmol of salt, and #5 refers to 49 mmol of salt.

FIG. 27 illustrates change in yield stress as result of variousconcentrations of ions in a slurry. Generally, magnesium salts initiallyhave high yield stresses and then demonstrate thinning. Generally,monovalent salts demonstrate thickening upon addition of more saltbefore slight thinning at even higher concentrations. Generally,trivalent salts and dibasic aluminum acetate show little to no yieldstress at a solution concentration.

Materials, devices, systems and methods herein, including materialcompositions (e.g., material layers), can be combined with or modifiedby other materials, devices, systems and methods, including materialcompositions, such as, for example, those described in U.S. PatentPublication No. 2013/0171471; U.S. Patent Publication No. 2013/0309410;U.S. Patent Publication No. 2013/0252022; U.S. Patent Publication No.2015/0167131; and U.S. Patent Publication No. 2015/0345041, each ofwhich is incorporated herein by reference in its entirety.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. It is not intendedthat the invention be limited by the specific examples provided withinthe specification. While the invention has been described with referenceto the aforementioned specification, the descriptions and illustrationsof the embodiments herein are not meant to be construed in a limitingsense. Numerous variations, changes, and substitutions will now occur tothose skilled in the art without departing from the invention.Furthermore, it shall be understood that all aspects of the inventionare not limited to the specific depictions, configurations or relativeproportions set forth herein which depend upon a variety of conditionsand variables. It should be understood that various alternatives to theembodiments of the invention described herein may be employed inpracticing the invention. It is therefore contemplated that theinvention shall also cover any such alternatives, modifications,variations or equivalents. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

1-132. (canceled)
 133. A method for forming, adjacent to a substrate, alayer of stainless steel comprising a transition metal, the methodcomprising: (a) coating at least a portion of said substrate with aslurry to generate a slurry-coated substrate, which slurry comprises:(i) a solvent; (ii) an alloying agent comprising said transition metal;(iii) a metal halide activator configured to facilitate diffusion of anamount of said transition metal in said slurry into said substrate,wherein a molar ratio of a halide of said halide activator to saidtransition metal is at most about 10:1; and (iv) an inert species thataids in dispersing said alloying agent in said solvent; wherein saidslurry does not comprise an organic binder; and (b) subjecting saidslurry-coated substrate to annealing under conditions that aresufficient to diffuse said amount of said transition metal in saidslurry into said substrate, to generate said layer of stainless steelcomprising said transition metal adjacent to said substrate.
 134. Themethod of claim 133, wherein said annealing conditions in (b) comprisean annealing atmosphere comprising hydrogen (H₂).
 135. The method ofclaim 133, wherein said annealing conditions in (b) comprise anannealing temperature is from about 800° C. to 1300° C.
 136. The methodof claim 133, wherein, during (b), at least about 95% of said transitionmetal in said slurry diffuses into said substrate.
 137. The method ofclaim 133, wherein, prior to (b), said slurry-coated substrate comprisesa dry film of said slurry, which dry film is capable of surviving a rollcoating process.
 138. The method of claim 137, wherein said dry film hasa green strength suitable to survive flexing to a 20 inch diameter arc20 times (positive and negative).
 139. The method of claim 138, whereinsaid dry film is capable of passing a tape test with small amount ofpowdering.
 140. The method of claim 133, wherein, prior to (a), saidsubstrate is provided in a coil; and wherein said coil is unwound priorto said coating in (a).
 141. The method of claim 140, wherein, after(a), said unwound coil is wound into a coated coil.
 142. The method ofclaim 133, wherein, prior to (a), said substrate is provided as a wire,pipe, tube, slab, a coiled mesh, a dipped formed part, a sheet, a wirerope, or a rod.
 143. The method of claim 133, wherein, in (a), saidcoating is via one or more selected from the group consisting of rollcoating, dipping, painting, spin coating, printing, spraying, slotcoating, curtain coating, slide coating, and extrusion coating.
 144. Themethod of claim 133, further comprising, in (a), coating said at leastsaid portion of said substrate with said slurry in multiple cycles. 145.The method of claim 133, wherein said layer of stainless steel comprisesan outer layer and a bonding layer adjacent to said outer layer. 146.The method of claim 145, wherein said transition metal has aconcentration that varies by less than about 20 wt. % in said outerlayer.
 147. The method of claim 145, wherein said transition metal has aconcentration that decreases to less than about 1.0 wt. % in saidbonding layer.
 148. The method of claim 145, wherein said layer ofstainless steel further comprises a core region adjacent to said bondinglayer; which core region comprises substantially the same composition assaid substrate.
 149. The method of claim 133, wherein said alloyingagent is selected from the group consisting of iron, chromium, nickel,vanadium, titanium, tungsten, molybdenum, cobalt, manganese, zirconium,niobium and combinations thereof.
 150. The method of claim 133, whereinsaid transition metal is selected from the group consisting of chromium,nickel, aluminum, silicon, vanadium, titanium, boron, tungsten,molybdenum, cobalt, manganese, zirconium, niobium and combinationsthereof.
 151. The method of claim 133, wherein said metal halideactivator is selected from the group magnesium chloride (MgCl₂), iron(II) chloride (FeCl₂), calcium chloride (CaCl₂)), zirconium (IV)chloride (ZrCl₄), titanium (IV) chloride (TiCl₄), niobium (V) chloride(NbCl₅), titanium (III) chloride (TiCl₃), silicon tetrachloride (SiCl₄),vanadium (III) chloride (VCl₃), chromium (III) chloride (CrCl₃),trichlorosilance (SiHCl₃), manganese (II) chloride (MnCl₂), chromium(II) chloride (CrCl₂), cobalt (II) chloride (CoCl₂), copper (II)chloride (CuCl₂), nickel (II) chloride (NiCl₂), vanadium (II) chloride(VCl₂), ammonium chloride (NH₄Cl), sodium chloride (NaCl), potassiumchloride (KCl), molybdenum sulfide (MoS), manganese sulfide (MnS), irondisulfide (FeS₂), chromium sulfide (CrS), iron sulfide (FeS), coppersulfide (CuS), nickel sulfide (NiS) and combinations thereof.
 152. Acomposition for forming a layer of stainless steel comprising atransition metal, the composition comprising: a slurry comprising: (i) asolvent; (ii) an alloying agent comprising said transition metal; (iii)a metal halide activator configured to facilitate diffusion of an amountof said transition metal in said slurry into said substrate, wherein amolar ratio of a halide of said halide activator to said transitionmetal is at most about 10:1; and (iv) an inert species that aids indispersing said alloying agent in said solvent, wherein said slurry doesnot comprise an organic binder; and wherein said slurry is configured toform said layer of stainless steel comprising said transition metal upondiffusion of said amount of said transition metal in said slurry into asubstrate.